<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style>
			.bo{
				width:500px;
				height:500px;
				position: relative;
			}
			.border-common-mini {
				position: absolute;
				width: 10px;
				height: 10px;
			}
			.border-left-top-mini {
				top: 0;
				left: 0;
				border-left: 2px solid #0394FF;
				border-top: 2px solid #0394FF;
			
			}
			.border-right-top-mini {
				top: 0;
				right: 0;
				border-right: 2px solid #0394FF;
				border-top: 2px solid #0394FF;
			
			}
			.border-left-bottom-mini {
				bottom: 0;
				left: 0;
				border-left: 2px solid #0394FF;
				border-bottom: 2px solid #0394FF;
			
			}
			.border-right-bottom-mini {
				bottom: 0;
				right: 0;
				border-right: 2px solid #0394FF;
				border-bottom: 2px solid #0394FF;
			
			}
		</style>
	</head>
	<body>
		<div class="bo">
			<div  class="border-common-mini border-left-top-mini"></div>
			<div class="border-common-mini border-right-top-mini"></div>
			<div class="border-common-mini border-left-bottom-mini"></div>
			<div class="border-common-mini border-right-bottom-mini"></div>
		</div>
	</body>
</html>
